1. Field of the Invention
The present invention relates to a recording apparatus and a method for forming a matrix of plural dots for use therein, and more particularly to a recording apparatus, and a recording method for use therein, for forming each pixel (picture element) corresponding to the recording data by a dot matrix.
2. Related Background Art
The method of forming each pixel with a dot matrix is known as one of the methods generally used for recording the image involving tonal gradation (harmonization), and produces multiple density levels by varying the number and position of the dots constituting the matrix.
It is also known, even when the tonal gradation is not required, to vary the dot shooting, or shoot or form plural dots on the same position for increasing the image density. It is furthermore known that, in the ink jet recording apparatus, each pixel can be simply formed with a dot matrix, by the recent development of high-resolution recording head, with extremely reduced dimensions of discharge ports and distances thereof.
On the other hand, such ink jet recording apparatuses are becoming widely used in various image recording apparatuses such as copying machines or facsimile apparatuses, and the recording media used therein are no longer limited to the coated paper exclusively designed for recording but have been diversified, including for example plain paper and overhead projector (OHP) films.
Such recording media are different in ink absorbing ability, and recording on a recording medium with low ink absorbing ability may result in deterioration of the recorded image quality, due to the ink mixing among different pixels resulting from ink blotting. The influence of such ink blotting on the image quality is particularly evident in case of color image recording, in which inks of different colors are in mutual contact between different pixels.
For this reason, in case of forming each pixel by the above-mentioned dot matrix on plain paper or the like with low ink absorbing ability, a vertical dot column between adjacent matrixes may be conventionally left as a blank for absorbing the ink, thereby reducing the influence of ink blotting.
In such method, however, because all the vertical dot columns between the adjacent matrixes are left blank, the pixels appear as streaks and the overall density is lowered, whereby the recorded image quality may be eventually deteriorated.
It is also known, in the recording on a medium with low ink absorbing ability such as an OHP film, to obtain a desired density by forming each dot by so-called overlay printing in which plural ink dots are overlaid, thereby causing spreading of ink on the recording medium.
However, in such conventional methods of leaving a dot column blank, the spreading of ink tends to take place only in a certain direction (namely in the direction of said vertical dot column), to result in uneven ink spreading, whereby the image density may be not only unable to reach the desired level but also may become uneven.